A novel strategy for arsenic phytoremediation

项目摘要： 食物链中的砷污染是一个全球性的健康问题，对大多数人体器官造成损害。 存在开发用于解决环境砷的方法的显著需要。长期目标是 为受污染的土地制定一种基于植物的植物补救办法，这种办法既具有成本效益，又具有生态效益 作为传统补救方法的替代方案。本研究的目的是开发一种 基于遗传学的植物修复策略，用于砷的吸收、转运、解毒和 在这种情况下，高生物量的非粮食作物海甘蓝（Crambe abyssinica）中的高积累量。纳米硫将是 用于调节土壤中As的生物有效性和植物提取，并增加储存容量 通过增强硫同化作用。工程Crambe将被评估为从土壤中去除砷， 实验室、温室和田间条件。我们的中心假设是器官特异性基因表达， 控制As的运输、氧化态和结合，可以调节以产生有效的提取， 超积累到地上植物组织中。为了验证我们的假设，我们提出了以下具体的 目标。1)用于共表达细菌ArsC、gECS和AtABCC 1的遗传工程化海甘蓝品系 和内源性砷酸盐还原酶CaACR 2的RNAi抑制; 2）评估工程化的Crambe系 3）合成和应用纳米硫以调节生物利用度， 植物提取和有毒金属（loids）的积累;以及4）进行工程Crambe的试点实地研究 在受污染场地进行植物提取的管线。在补充有以下物质的组织培养基中进行初始筛选后， 金属，表现最好的四重基因堆叠（ArcS+gECS+ AtABCC 1 + CaACR 2 Ri）Crambe系与野生型 将在温室中使用受砷污染的土壤以及共污染物对类型控制进行测试。一 然后，将在一个受砷污染的地点进行实地规模的试验研究。土壤将广泛 进行表征，并使用ICP/MS、HPLC-进行金属含量和砷形态分析 ICP/MS以及XANES（X射线吸收近边缘光谱）。最后，土壤改良剂与工程 纳米硫将用于评估对土壤结构和污染物可用性以及植物提取的影响。 纳米硫也将被叶面施用到植物上，通过增强硫来增加金属储存能力。 同化该项目的预期成果是对生物地球化学的机理性理解， 将关键土壤特性与植物提取效率相结合的砷修复植物过程 和砷的过度积累。结果将产生直接和重要的积极影响，因为 从这项研究中产生的知识将使高效和有效的植物修复方法， 减少或消除食物链中的砷污染，并提高公众健康。

Project Summary: Arsenic contamination in the food chain is a global health problem and causes damage to most human organs. A significant need exists to develop approaches for addressing environmental arsenic. The long term goal is to develop a plant-based phytoremediation approach for contaminated land that is cost-effective and ecologically friendly as an alternative to conventional remediation methods. The objective of this study is to develop a genetics-based phytoremediation strategy for arsenic uptake, translocation, detoxification, and hyperaccumulation into the fast-growing, high biomass, non-food crop Crambe abyssinica. Nanosulfur will be utilized to modulate the bioavailability and phytoextraction of As from soil and to increase the storage capacity via enhanced sulfur assimilation. The engineered Crambe will be evaluated for removing arsenic from the soil in laboratory, greenhouse, and field conditions. Our central hypothesis is that organ-specific expression of genes, which control the transport, oxidation state, and binding of As, can be tuned to yield efficient extraction and hyperaccumulation into above-ground plant tissues. To test our hypothesis, we propose the following specific aims. 1) Genetically engineer Crambe abyssinica lines for co-expressing bacterial ArsC, gECS, and AtABCC1 and RNAi suppression of endogenous arsenate reductase CaACR2; 2) Evaluate the engineered Crambe lines for metal(loids) tolerance and accumulation; 3) Synthesize and apply nanosulfur to modulate the bioavailability, phytoextraction, and accumulation of toxic metal(loids); and 4) Conduct a pilot field study of engineered Crambe lines for phytoextraction on a contaminated site. After initial screening in tissue culture media supplemented with metals, the best performing quadruple gene stacked (ArcS+gECS+AtABCC1+CaACR2Ri) Crambe lines with wild type controls will be tested using contaminated soils with arsenic as well as co-contaminants in greenhouse. A pilot field-scale study will then be carried out at a site contaminated with arsenic. The soil will be extensively characterized, and analysis for metal content and arsenic speciation will be determined using ICP/MS, HPLC- ICP/MS as well as XANES (X-ray Absorption Near-Edge Spectroscopy). Last, soil amendments with engineered nanosulfur will be used to evaluate the impacts on soil structure and contaminant availability and phytoextraction. Nanosulfur will also be foliarly applied to plants to increase the metal storage capacity via enhanced sulfur assimilation. The expected outcome of this project is a mechanistic understanding of the biogeochemical and plant processes of arsenic remediation that connects key soil characteristics with the efficiency of phytoextraction and hyperaccumulation of arsenic. The results will have an immediate and important positive impact because the knowledge generated from this study will enable efficient and effective phytoremediation approaches to minimize or remove arsenic contamination in the food chain and enhance public health.